AT a time when family finances are under stress and forecasts remain resolutely bleak, Professor Bernard Fortin brings news of a new economic indicator – the teenage girl.

The Mail has studied his work, which is based on National Statistics records of family spending during the 1980s and 1990s.

This leads us to the conclusion that if Britain’s manufacturing base is to grow, then we should start producing Walkmans, ankle-warmers and ra-ra skirts. Or rather, to bring things up to date: handbags, mobile phones, and the myriad must-have accessories without which today’s teen cannot be seen dead.

Offspring over 21 have no influence on family spending, even if they are contributing to the communal coffers. Young children have more limited (and cheaper) tastes, and can be punished by withholding these things.

Teenage boys, however, did not appear to influence household spending at all – a fact that the researchers could not explain. Anorak suspects this could be related to the generally disreputable nature of adolescent male consumption, most of which would be unsuited to a family budget – or, indeed, a family website such as this.